Project Summary The 2018 Chemistry & Biology of Tetrapyrroles Gordon Research Conference (GRC) builds upon a long and rich tradition which started over 50 years ago in 1966 with a group of scientists with diverse interests and strengths but with a common core interest in understanding tetrapyrroles ? a family of small metabolites comprising heme, cobalamin (B12), and chlorophyll. Each of these compounds are essential for sustenance of life on the planet and are synthesized from the same biochemical pathway. Even though these are essential prosthetic groups they are also toxic thereby requiring intricate regulation and coordination. How these tetrapyrroles are ultimately trafficked to the correct cellular destination and inserted into target proteins (eg: hemoglobin) are poorly understood and represents a significant knowledge gap. Furthermore, tetrapyrroles are also degraded giving rise to bioactive products which can act as antioxidants (bilirubin) and light harvesting pigments (bilins). Therefore, the main scientific theme of the 2018 Chemistry & Biology of Tetrapyrroles GRC is to deliberate on the recent advances in The Movement and Trafficking of Tetrapyrroles. The 2018 GRC meeting will be held from July 15 - 20, 2018 at Salve Regina University, Newport, RI. There is no other meeting internationally that encompasses the scope in terms of clinical, biological, and chemical aspects of tetrapyrroles from microbes to man as does the Chemistry & Biology of Tetrapyrroles GRC. The meeting is held every two years and attracts about 140 attendees. Participants are drawn from a wide variety of disciplines including clinicians, basic biologists, chemists, engineers, and physicists with expertise in solving outstanding problems associated with the chemistry and catalysis of tetrapyrroles; heme synthesis, porphyrias and its pathophysiology; regulatory pathways in chlorophyll and energy production; heme trafficking and imaging; linear tetrapyrroles and photoreceptors; biosynthesis, trafficking and homeostasis of B12 and corrinoids; degradation and signaling of tetrapyrroles; tetrapyrroles at the host-pathogen interface; and tetrapyrrole metabolism in human inherited disorders. Given that tetrapyrroles share common chemical properties, the biological principles that govern their trafficking and homeostasis are likely to have overarching similarities across phyla thereby permitting us to derive inferences which can ultimately nucleate and synergize new discoveries that can positively impact human health.